1. Field of the Invention
This invention relates to a continuous process for producing room temperature vulcanizable (RTV) silicone rubber compositions, especially of the one-part type.
2. Prior Art
For the continuous production of RTV silicone rubber compositions, Stary et al., U.S. Pat. No. 4,737,561 proposed a process using a pilgrim-step kneader. This process involves a first step of mixing an organopolysiloxane oil, a filler (typically inorganic filler) and optional components in a closed mixer to form a silicone rubber compound and a second step of metering the remaining components into the compound in an oscillating pilgrim-step mixer where the mixture is homogenized and degassed. This process, however, has the problem that since the mixture in the second step becomes gel and sticks to the mixing machine, the machine must be frequently disassembled and cleaned. This results in a considerably low production efficiency.
It is thus desired to overcome the problems of prior art processes, that is, to provide a continuous process for producing an RTV silicone rubber composition, especially an RTV silicone rubber composition having anti-sagging properties in such a manner as to improve the efficiency of continuous production over the prior art processes. Since a composition of this type is typically contained in a container such as a cartridge or tube, it is further desired to improve the applicability (ease of discharging and anti-stringing) of the composition.